What Are the Pros and Cons of Downdraft Ventilation?

I've considered buying one instead of the conventional range hood, in order to maximize space in the kitchen and also to create a more modern, minimal look. But I am worried that downdrafts are not as effective in exhausting the odors and fumes while cooking in comparison to range hoods. Any advice?

Sent by Elena

Editor: Elena, I am in a funny position of wishing I could give you feedback on a downdraft ventilation system. See, I have one in my old rental kitchen (the pop-up action was a major surprise, on moving in) but it doesn't actually work. You can see it in a video here: